 Abstract self-assembly of amyloid peptids leads to oligomers, proto-fibrils, and fibrils that are likely instigators of neurodegeneration in Alzheimer's disease. Using time-resolved solid-state NMR and light-scattering experiments, we observe that 40-residue amyloid A40 forms oligomers, proto-fibrils, and fibrils on time scales ranging from 0.7 mL to 1H after initiation of self-assembly by a rapid pH drop. The low-temperature NMR spectra of freeze-trapped intermediates indicated that strands within and contacts between the two main hydrophobic segments of A40 developed within 1 mL, while light-scattering data suggested a primarily monomeric state up to 5 mL, into molecular contacts involving residues 18 and 33 developed within 0.5 s, at which time A40 was approximately octomeric. These contacts argued against sheet organization resembling those found previously in proto-fibrils and fibrils. This article was authored by Jackie and John, Yming Yao, and Robert Tico. We are article.tv, links in the description below.